Arias, 34, eluded the death sentence last month after a lone juror at her sentencing retrial refused to back the death penalty throughout five days of deliberations.

She was found guilty of murder in 2013 after a trial packed with lurid details and graphic testimony. Prosecutors said she killed her former partner in a jealous rage, while Arias argued she acted in self-defense.

Shackled and clad in jail stripes, Arias told the court she had long wanted to be put to death for the crime.

"But I had to fight for my life just like I did on June 4, 2008, because I realized how selfish it would be for me to escape accountability for this mess I created," Arias said.

She said she remembered the moment she plunged the knife into Travis Alexander's throat.

"He was conscious. He was still trying to attack me. It was I who was trying to get away, not Travis, and I finally did," she said. "I never wanted it to be that way."

The 30-year-old victim was found in a shower at his Phoenix-area home. He had been shot in the face and stabbed more than 20 times, and his throat was slashed almost from ear to ear.

Eleven of the jurors from Arias' retrial were in court for the sentencing, wearing blue clothing and ribbons in memory of the victim. The holdout juror did not attend.

After they failed last month to reach a unanimous verdict on whether she should be executed, Stephens had to choose between sentencing Arias to life in prison or to life with the possibility of parole after 25 years.

"The defendant did not render aid to the victim ... (and) destroyed evidence at the crime scene. The defendant went to great lengths to conceal her involvement," Stephens said.

"The court finds the mitigation presented is not sufficiently substantial to call for leniency and that a natural life sentence is appropriate."

Samantha Alexander, a younger sister of the victim, told the court Arias had sought to smear Travis throughout and that she deserved to be put to death.

"She continuously makes atrocious lies about my brother, dragging his name through the mud like she dragged his body through his own blood," she said.

"I wouldn't waste my time addressing her because she isn't worth my breath."

Defense attorney Jennifer Willmott said Arias was remorseful and had urged the judge to give her the hope of release one day.

"Ms. Arias is not a monster," Willmott said. "For two minutes in her life she did something reprehensible ... she is disgusted by what she did."